Wave Overtopping of Stepped Revetments

Abstract

Wave overtopping—i.e., excess of water over the crest of a coastal protection infrastructure due to wave run-up—of a smooth slope can be reduced by introducing slope roughness. A stepped revetment ideally constitutes a slope with uniform roughness and can reduce overtopping volumes of breaking waves up to 60% compared to a smooth slope. The effectiveness of the overtopping reduction decreases with increasing Iribarren number. However, to date a unique approach applicable for a wide range of boundary conditions is still missing. The present paper: (i) critically reviews and analyzes previous findings; (ii) contributes new results from extensive model tests addressing present knowledge gaps; and (iii) proposes a novel empirical formulation for robust prediction of wave overtopping of stepped revetments for breaking and non-breaking waves. The developed approach contrasts a critical assessment based on parameter ranges disclosed beforehand between a smooth slope on the one hand and a plain vertical wall on the other. The derived roughness reduction coefficient is developed and adjusted for a direct incorporation into the present design guidelines. Underlying uncertainties due to scatter of the results are addressed and quantified. Scale effects are highlighted.

Flooding of Piazza San Marco (Venice): Physical Model Tests to Evaluate the Overtopping Discharge

“…Clearly, the number of steps, as well as their dimensions, influence the energy dissipation. This agrees with the results of Kerpen et al [17]. The pictures in Figure 9 give a qualitative description of the wave-structure interaction at the quay border.…”

“…The presence of the steps is ignored since it has a minor and uncertain influence on the measured overtopping discharge. The reduction effect found by Kerpen et al [17] is relative to a stepped revetment that continues down to the bottom with no vertical wall, i.e., a geometry significantly different from section C.…”

“…The investigation could be useful to select an appropriate adaptation measure that reduces overtopping, minimizing the impact and considering the historic and architectural constraints of the city of Venice. Among the measures and solutions that reduce the amount of overtopping, those that may be considered are, for instance, the addition of structural elements to the quay wall such as berms Burcharth et al [15], crown walls Van Doorslaer et al [13], Formentin et al [16], steps Kerpen et al [17], McCabe et al [18], bullnoses Pearson et al [19], Martinelli et al [20]; the promenade upgrades Van Doorslaer et al [21], De Finis et al [22] combined to the addition of stilling wave basins Geeraerts et al [23], Kisacik et al [24] or overspill basin Grossi et al [25], Cappietti et al [26]; the reduction of the waves incident the quay by floating breakwaters Ruol et al [27].…”

A Hydraulic Experimental Study of a Movable Barrier on a Revetment to Block Wave Overtopping

“…All overtopping discharges are less than the allowable limit for the standing barrier. In order to cope with wave overtopping more efficiently, it is necessary to properly design energy dissipators on the movable barrier, such as wave return walls [23] or stepped revetments [24], to reduce the height of the barrier. Reducing the height of the barrier would be excellent in terms of utilizing the surrounding space and view.…”

Experimental Study on the Influence of Berms and Roughness on Wave Overtopping at Rock-Armoured Dikes

“…Those influence factors suggested by [13] have been applied to the neural network prediction of overtopping (see for instance [7]). However, some research (e.g., [14][15][16][17]) showed that the roughness influence factors are not constant but change with wave conditions and structure configurations. Until now, there is no validated method available to evaluate the roughness influence factor of rock armour taking the effects of wave conditions and dike configurations into account.…”